The present invention relates to Light Emitting Diodes (LEDs), and more particularly to the design and use of LED modules for various illumination applications, such as commercial signs, street signs, channel letter signs, etc. The invention utilizes module designs that are flexible in mounting method, electrical connection method, LED array arrangements and optical designs.
Light Emitting Diodes (LEDs) have been used in many applications to replace conventional incandescent lamp, fluorescent lamp, neon tube and fiber optic light sources in order to reduce electrical and maintenance costs and to increase reliability and lifetime. One such application is channel letter signs, which are signs having sidewalls and a front translucent face formed in the shape of a letter, number or other insignia. Conventional light sources, such as neon tubes, have been used to illuminate the front translucent face of such signs. Neon tubes are ideal for channel letter signs because they can be shaped to fit into narrow, shaped channels. However, neon tubes consume significant energy and require high voltage to operate. Further, neon tubes do not function well in low temperatures. Fiber optics have been used as the light source (see U.S. Pat. No. 6,024,476 by Wakeman). However, even though the use of fiber optic sources provides more flexibility, this solution is still energy consuming and exhibits a limited life time.
Due to the fact that LEDs consume less electrical energy than conventional light sources while exhibiting much longer lifetime, many designs are now being developed specifically for applications such as channel letter signs utilizing LEDs. For example, PermLight of Tustin, Calif. markets an LED based light for channel letter signs, wherein the light attaches to the side wall of the sign. The output light is directed toward the bottom wall, which scatters the light to illuminate the interior of the sign, including the front translucent surface. There are several major disadvantages of this design. The reflectivity of the bottom surface of the channel letter sign can decrease with time due to surface degradation. Further, when the channel is wide, the illumination from the LED based lamp may not be very even or the light intensity may not be enough because of the large surface area that it needs to cover. Moreover, illumination efficiency is rather low because the front surface of the sign is not directly illuminated, but rather is illuminated after the light undergoes reflections off of the interior surfaces of the sign bottom walls.
SloanLED of Ventura, Calif. markets LED strips that can be disposed in channel letter signs. However, the LED strips are hard or impossible to install around the curved portions of the channel letter, and illumination can be very uneven, especially when the depth of the channel letter is shallow or varies.
Hi-Tech Electronic Displays of Clearwater, Fla. offers a flexible metal clip with LEDs for channel letter sign applications. The major disadvantages of this design are that its installation and electrical connections are rather complicated (requiring a special insertion tool to add LEDs), and it is unclear how to move installed LEDs if illumination is insufficiently uniform.
Other types of illuminated signs include commercial and street signs, where LED arrays are used to illuminate the sign plate from the sides of the plate, as shown in Chen (U.S. Pat. No. 6,027,235), Durbin (U.S. Pat. No. 6,023,869) and Woo (U.S. Pat. No. 5,950,340). Often times, due to the poor coupling of the light to the plate and the limitation on the.number of LEDs that can be installed on the sides, light intensity may not be sufficient for many applications.
The objective of the present invention is to provide an LED module design that can be easily installed in all applications and is flexible in the method of electrical connection and arrangement of the LED""s. Such LED module designs should be usable in channel letter and commercial signs of any size and with basically any light intensity requirements.
The present invention solves the aforementioned problems by providing LED modules that can be easily located throughout the interior of translucent signs for even illumination thereof.
The light emitting diode module of the present invention attaches to a surface of a sign, and includes a housing, a plurality of light emitting diodes mounted to a top surface of the housing, a plurality of first electrical connectors attached to side surfaces of the housing and electrically connected to the plurality of light emitting diodes, means for attaching a bottom surface of the housing to a surface of a sign, and a power supply for providing a voltage to the light emitting diodes via at least one of the first electrical connectors.
In another aspect of the present invention, the light emitting diode module includes a mounting plate having top and bottom surfaces, a plurality of light emitting diodes mounted to the top surface of the mounting plate, a housing having top and bottom surfaces, a first electrical connector attached to the bottom surface of the mounting plate and electrically connected to the plurality of light emitting diodes, a second electrical connector attached to the top surface of the housing for engaging with the first electrical connector, a third electrical connector attached to the housing and electrically connected to the second electrical connector, and a power supply for providing a voltage to the third electrical connector, wherein, as the bottom surface of the mounting plate is placed on the top surface of the housing, the first electrical connector engages with the second electrical connector for electrically connecting the plurality of light emitting diodes to the third electrical connector.
In yet another aspect of the present invention, an illuminated sign includes a back wall, a translucent front face that opposes the-back wall, a sidewall that is attached between the back wall and the front face, a power supply and a plurality of LED modules. Each LED module includes a housing having top and bottom surfaces, a plurality of light emitting diodes mounted to the top surface of the housing, and a first electrical connector attached to the housing and electrically connected to the plurality of light emitting diodes. The power supply provides a voltage to the first electrical connectors. For each of the LED modules, the bottom surface of the housing is attached to the back wall so that the plurality of light emitting diodes faces the front face.
In yet one more aspect of the present invention, the illuminated sign includes a back wall, a translucent front face that opposes the back wall, a sidewall that is attached between the back wall and the front face, a power supply, and a plurality of LED modules. Each LED module includes a mounting plate having top and bottom surfaces, a plurality of light emitting diodes mounted to the top surface of the mounting plate, a housing having top and bottom surfaces, a first electrical connector attached to the bottom surface of the mounting plate and electrically connected to the plurality of light emitting diodes, a second electrical connector attached to the top surface of the housing for engaging with the first electrical connector, and a third electrical connector attached to the housing and electrically connected to the second electrical connector. As the bottom surface of the mounting plate is placed on the top surface of the housing, the first electrical connector engages with the second electrical connector for electrically connecting the plurality of light emitting diodes to the third electrical connector. The power supply provides a voltage to the third electrical connectors. For each of the LED modules, the bottom surface of the housing is attached to the back wall so that the plurality of light emitting diodes faces the front face.
Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures.